THE 
NEW PHYTOhOGIST. 
__ * _ . \ 
Vol. V., No. 9. November 30TH, 1906. 
LECTURES ON THE PHYSIOLOGY OF MOVEMENT 
IN PLANTS. 
By Francis Darwin. 
1 .—Associated Stimuli. 
I SHALL begin my Lectures on Plant-Movement with a general 
discussion on the reaction of plants to Stimulus. 
The first clear statement of the present point of view occurs 
in that often quoted passage in Dutrochet * 1 * * * * * in which he declares 
that the movements are “ spontaneous,” being executed “ a l’occa- 
sion de l’influence d’un agent exterieur, et non des mouvements 
imprimes par cet agent.” A discussion of the meaning of the 
word spontaneous would lead us too far. On the other hand, if we 
deny to living organisms what is commonly known as spontaneity, 
we are driven to adopt automatonism. 
No doubt if we take a severely logical view of the universe 
with Descartes, we may be obliged to admit that our actions are 
the direct inevitable result of what has previously occurred in the 
world, and that we are forced into a certain action just as inevitably 
as the mercury in a thermometer is forced to rise to a certain 
point. But this is a point of view which leads us no further, it is 
not an instrument of research. To get a point of view which 
is physiologically valuable we must retain the idea of spontaneity. 
What we do at a particular juncture depends on the nature of 
our previous experiences and actions. The “ self ” which seems to 
be spontaneous is the balance which w 7 eighs conflicting influences. 
' Quoted by Pfeffer from Dutrochet, Recherches anat. sur la 
Structure, &c., 1824, p. 107. 
